An optoelectronic technique for synthesis of frequency-versatile electrical signals phase-locked to the optical clock is proposed. The key component is an integrated-optic modulator (IOM) operated in the nonlinear regime. With a photodetctor, the IOM functions as an optoelectronic subharmonic mixer for intermixing microwave signals that are subharmonics of the optical clock, As a first demonstration, phase-locked subharmonics and fractional harmonics of the optical clock at f(o) = 500 MHz, with frequency equal to f(o)/n or (m/n)f(o), where n = 2,3,4... and m/n = 2/5,2/3,4/3,3/2 and 5/3 etc;, are generated and characterized.